Thus far, attempts have been made to improve the mechanical characteristics and the like of a resin by conjugating (mixing) an inorganic oxide, such as silica, as a filler and the resin. An ordinary method of conjugating the filler and the resin is a method in which a dispersion fluid containing the inorganic oxide dispersed in water or an organic solvent and the resin or resin raw material components are mixed. It is possible to manufacture metal oxide particle-conjugated plastic in which inorganic oxide particles are conjugated in a resin by mixing a dispersion fluid, the resin and the like by a variety of methods as a second phase (for example, refer to Patent Literature 1).
Among resins, silicone resins are used in a wide range from cosmetic materials or biomedical materials to electrical or electronic materials due to their excellent weather resistance characteristics, such as heat resistance and cold resistance, excellent electrical characteristics, low toxicity, and the like. In addition, recently, attention has been given to their transparency, and thus silicone resins have been used in optical members, such as a transparent sealing material and the like of a light-emitting diode. The optical members need to have properties, such as optical characteristics such as transparency and refractive index, mechanical characteristics such as hardness, and thermal stability such as heat resistance.
Generally, in a case in which a resin and an inorganic material such as an inorganic oxide are conjugated so as to obtain a composite, a variety of methods in which the compatibility between an inorganic material and a resin is improved by modifying the surface of the inorganic material, or previously conjugated raw materials are polymerized so as to obtain a composite are used.
For example, in a case in which inorganic oxide particles are conjugated with a hydrophobic resin, since the surfaces of the inorganic oxide particles are hydrophilic at all times, there was a problem that the inorganic oxide particles are not easily dispersed in the hydrophobic resin. Therefore, as a general solution, efforts have been made to make the surfaces of the inorganic oxide particles hydrophobic and increase the compatibility between the resin and the inorganic oxide particles by adding a surface modifier, such as an organic polymer dispersant, to the surfaces of the inorganic oxide particles.
However, in a case in which a silicone resin is selected as the resin, the silicone resin is highly hydrophobic. Therefore, it is difficult to make the surfaces of the inorganic oxide particles hydrophobic until the inorganic oxide particles are dissolved together with the silicone resin, which creates a problem that the silicone resin and the inorganic oxide particles are separated, and it is difficult to conjugate the silicone resin and the inorganic oxide particles.
Therefore, in order to conjugate the silicone resin and the inorganic oxide particles so as to obtain a conjugated plastic having favorable optical characteristics or thermal stability, for example, a composition in which zirconium oxide particles are conjugated with a hydroxyl group-containing polysiloxane in the presence of a chelating agent is proposed (Patent Literature 2).
In addition, a composition for coating light-emitting elements in which zirconium oxide particles and a polyfunctional polysiloxane are conjugated is also proposed (Patent Literature 3).